AN ACOUSTIC COUPLING INTERFACE

Abstract

The present invention provides an acoustic coupling interface (1) for use between a flexible ultrasound transducing device (2) and a curved object (3) to be examined. The interface (1) is in the form of a sheet (4) having a bending flexibility that permits the sheet (4) to form a continuous contact with said curved object (3) during operation of the flexible ultrasound transducing device (2). Further, the sheet (4) comprises a bulk material (5) and a plurality of acoustic waveguiding structures (6) arranged in said bulk material (5), wherein the plurality of acoustic waveguiding structures (6) is for providing bidirectional coupling of ultrasound signals (7) emitted by the ultrasound transducing device (2).

Claims

1. An acoustic coupling interface for use between a flexible ultrasound transducing device and a curved object to be examined, wherein said interface is in the form of a sheet having a bending flexibility that permits the sheet to form a continuous contact with said curved object during operation of the flexible ultrasound transducing device, and wherein said sheet comprises a bulk material and a plurality of acoustic waveguiding structures arranged in said bulk material, wherein the plurality of acoustic waveguiding structures is for providing bidirectional coupling of ultrasound signals emitted by the ultrasound transducing device.

2. An acoustic coupling interface according to claim 1, wherein said sheet has a first planar surface arranged for contacting said flexible ultrasound transducing device and a second planar surface, opposite said first surface, arranged for contacting said curved object to be examined, and wherein said sheet has a bending flexibility such that the surface profiles of both the first and second planar surfaces are altered with the second planar surface conforming to the curved object when the sheet is in contact with said curved object during operation.

3. An acoustic coupling interface according to claim 2, wherein the first and second planar surfaces have a length and width that both are at least five times the thickness of the sheet.

4. An acoustic coupling interface according to claim 1, wherein the sheet has a bending flexibility that permits the sheet to be bent with a radius of curvature (Rc) that is less than 5 cm.

5. An acoustic coupling interface according to claim 1, wherein the plurality of acoustic waveguiding structures comprises waveguiding structures having an elongated form.

6. An acoustic coupling interface according to claim 2, wherein the plurality of acoustic waveguiding structures comprises an arrangement of alternating bulk material and another material different from the bulk material, said arrangement extending from the first planar surface to the second planar surface.

7. An acoustic coupling interface according to claim 2, wherein the plurality of acoustic waveguiding structures comprises waveguiding structures extending from the first planar surface to the second planar surface.

8. An acoustic coupling interface according to claim 1, wherein the plurality of acoustic waveguiding structures comprises a solid material different than the bulk material.

9. An acoustic coupling interface according to claim 7, wherein the plurality of acoustic waveguiding structures protrudes out from the first and/or second planar surface.

10. An acoustic coupling interface according to claim 1, wherein the plurality of acoustic waveguiding structures comprises internal walls in the bulk material so as to define waveguiding structures in the form of voids in the bulk material.

11. An acoustic coupling interface according to claim 1, wherein the bulk material comprises a polymer.

12. A system for creating data representative of features of a curved object comprising: a flexible ultrasound transducing device, and an acoustic coupling interface according to claim 1 configured to be removably attached to said ultrasound transducing device such that ultrasound signals emitted by the transducing device are transmitted into said object and resultant echo signals from the object are transmitted back to the ultrasound transducing device.

13. A system according to claim 12, wherein said flexible ultrasound transducing device comprises an array of ultrasound transducers.

14. A method of obtaining data representative of features of a curved object comprising: subjecting the object to ultrasound signals using a system according to claim 12; analysing the resultant echo signals from the object and thereby obtaining data representative of features of said object based on the resultant echo signals.

15. A method according to claim 14, wherein the step of subjecting the object to ultrasound signals is performed with a direct contact of the acoustic coupling interface and the object and/or a direct contact of the acoustic coupling interface and the flexible ultrasound transducing device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0070] The above, as well as additional objects, features and advantages of the present inventive concept, will be better understood through the following illustrative and non-limiting detailed description, with reference to the appended drawings. In the drawings like reference numerals will be used for like elements unless stated otherwise.

[0071] FIG. 1 is a perspective view of a schematic illustration of an acoustic coupling interface of the present disclosure.

[0072] FIGS. 2a-f are illustrative embodiments of the acoustic waveguiding structures arranged in the bulk material of the sheet.

[0073] FIG. 3 is a schematic illustration of the bend angle and the radius of curvature when the acoustic coupling interface is bent in negative Z-direction.

[0074] FIGS. 4a-d shows illustrative embodiments of a system s for creating data representative of features of a curved object during examination of an object.

[0075] FIG. 5 is a schematic illustration of a method of obtaining data representative of features of an object.

DETAILED DESCRIPTION

[0076] FIG. 1 shows a schematic example of an acoustic coupling interface 1 according to the present disclosure. The interface 1 is in the form of a sheet 4 that extends in an X-Y plane, with a thickness extending in a Z-direction perpendicular to both X and Y directions. The sheet 4 has a first planar surface 4a and a second planar surface 4b opposite the first planar surface 4a, and since the interface 1 is for use between a flexible ultrasound transducing device 2 and an object, such as a curved object 3, one of the planer surfaces may during use face the object 3 that is examined whereas the opposite planar surface faces the ultrasound transducing device. Consequently, the sheet 4 has a first planar surface 4a arranged for contacting said flexible ultrasound transducing device 2 and a second planar surface 4b, opposite said first surface 4a, arranged for contacting said curved object 3 to be examined.

[0077] The sheet 4 has in this example a rectangular or quadratic shape with a length d1 in the X direction of about 5-20 cm, such as about 10 cm and a length d2 in the Y-direction of about 5-20 cm, such as about 10 cm. The sheet is further thin in relation to the surface areas of the first 2a and second 2b planar surfaces, such as having a thickness d3 in the Z-direction of about 0.1 mm-1.0 mm. Thus, the first 4a and second 4b planar surfaces may have a length and width that both are at least fifty times the thickness of the sheet.

[0078] Moreover, the sheet 4 comprises a bulk material 5 and a plurality of acoustic waveguiding structures 6 arranged in the bulk material (5). In the example of FIG. 1, the acoustic waveguiding structures 6 are arranged as a two-dimensional array 9 in the bulk material 5.

[0079] The plurality of acoustic waveguiding structures 6 is for providing bidirectional coupling of ultrasound signals 7 emitted an ultrasound transducing device 2 during examination of an object 3.

[0080] FIGS. 2a-f shows different embodiments of acoustic waveguiding structures 6.

[0081] FIGS. 2a-f are section view of a sheet 4, e.g. a section view along line A of the sheet in FIG. 1.

[0082] FIG. 2a shows a schematic embodiment of acoustic waveguiding structures 6 arranged within the bulk material 5. The waveguiding structures 6 have an elongated form extending from the first planar surface 4a to the second planar surface 4b. Thus, the waveguiding structures 6 extend in the Z direction, i.e. in the direction in which the thickness of the sheet 4 is defined. The elongated waveguiding structures, or elongated waveguides 6, may have any suitable form, such as in the form of cylinders or having convex or concave outer forms.

[0083] FIG. 2b shows a schematic embodiment of acoustic waveguiding structures 6 arranged within the bulk material 5. In this example, the waveguiding structures 6 protrude from the second planar surface 4b.Thus, the waveguiding structures 6 comprises a portion 6a that extends or protrudes out from the second planar surface 6b. The second planar surface 4b may thus comprise an array of protruding portions 6b. The protruding portions 6a may aid in keeping the contact between the acoustic coupling interface 1 with an object 3 during examination by making the second outer planar surface 4b of the sheet 4 more sticky, i.e. by increasing the friction between the interface 1 and the object 3 during examination.

[0084] The acoustic waveguiding structures 6 may also protrude from the first planar surface 4a. This example is shown in FIG. 2c, in which the waveguiding structures 6 comprises a portion 6a that extends or protrudes out from the first planar surface 6a. The first planar surface 4a may thus comprise an array of protruding portions 6a. The protruding portions 6a may aid in keeping the contact between the acoustic coupling interface 1 and a flexible ultrasound transducing device 2 during examination by making the first outer planar surface 4a of the sheet 4 more sticky, i.e. by increasing the friction between the interface 1 and the flexible ultrasound transducing device 2 during examination.

[0085] The acoustic waveguiding structures 6 may also protrude both from the first planar surface 4a and the second planar surface 4b. Such an example is shown in FIG. 2d, in which the acoustic waveguiding structures 6 both comprises a portion 6a protruding out from the first planar surface 6a and a portion 6a protruding out from the second planar surface 6b.

[0086] Having such an arrangement of protruding portions 6a and/or 6b, using a gel between interface 1 and transducer array 2, or a gel between interface and the object 3 that is examined, may be unnecessary.

[0087] FIG. 2e shows a schematic embodiment of the sheet 4 in which plurality of acoustic waveguiding structures 6 is arranged within the bulk material 6 and comprises an arrangement 7 of alternating bulk material 6 and another material 6c different from the bulk material 6. The arrangement 7 extends in the Z-direction from the first planar surface 4a to the second planar surface 4b. The material 6c other than the bulk material is thus arranged as discrete elements within the bulk 4, e.g. along imaginary straight lines extending from the first planar surface 4a to the second planar surface 4b.The size of the discrete elements and the distance between adjacent discrete elements makes the arrangement 7 work as a guiding structure for ultrasonic waves propagating through the sheet 4.

[0088] FIG. 2f shows a further schematic embodiment of a sheet 4 comprising a plurality of acoustic waveguiding structures similar to the embodiment discussed in relation to FIG. 2a above, but the acoustic waveguiding structures 6 are in the form of voids 8a arranged within the bulk material 5. Thus, the plurality of acoustic waveguiding structures 6 comprises in this example internal walls 8 in the bulk material 6 so as to define waveguiding structures in the form of voids 8a in the bulk material 6.

[0089] The acoustic waveguiding structures 6 may be of a material having a different acoustic impedance than the bulk material 6. Thus, the plurality of acoustic waveguiding structures 6 may comprise a solid material different than the bulk material 5.

[0090] The acoustic waveguiding structures 6 may be or comprise a metal or polymer, and may form three-dimensional acoustic impedance objects within the bulk material 6.

[0091] The bulk material 6 may comprise a polymer, such as polyimide (PI). The bulk material may be a flexible material so that the sheet 4 becomes flexible. Thus, the sheet 4 may be flexible so as to form a continuous contact with a curved object 3 during operation of a flexible ultrasound transducing device 2. As an example, the sheet 4 may have a bending flexibility such that the surface profiles of both the first 4a and second b planar surfaces are altered during examination. The second planar surface, which is the surface in contact with or closest to the object being examined, may conform to the curved object 3 when the sheet 4 is in contact with a curved object 3 during examination. However, the sheet 4 may be flexible enough so that also the first planar surface 4a may conform to the curved object during examination.

[0092] Consequently, the acoustic coupling interface 1 may facilitate transfer of the surface profile of the object 3 being examined to a flexible ultrasound transducing device during examination.

[0093] FIG. 3 illustrates how the flexibility of the sheet 4 may be measured. In analogy with what is shown in FIG. 1, the first 4a and second 4b planar surfaces extend in an

[0094] X and Y direction and the sheet 4 has a thickness extending in a Z direction that is perpendicular to the X and Y directions. The sheet may have a flexibility and such that it may be bent in positive or negative Z direction with a bend angle (a) that is at least 30 degrees without breaking. The thickness of the sheet 4 may in combination with the material of the bulk material, be the most important factor influencing the flexibility of the sheet 4. When bending the sheet 4, the “breaking” may refer to cracks appearing on the outer surface during bending, i.e. the surface having an area under tension during the bending. In the Example shown in FIG. 3, this area would be the surface area of the second planar surface 2b.

[0095] Further, the radius of curvature Rc may be less than 5 cm without the sheet 4 breaking. The radius of curvature may be the inside curvature during bending. Thus, in FIG. 3, the radius of curvature is measured on the first planar surface 3a since the sheet 4 is bent in negative Z-direction.

[0096] FIGS. 4a-4d show different schematic and illustrative embodiments of a system 10 for creating data representative of features of an object 3.

[0097] As shown in FIG. 4a, the system 10 comprises a flexible ultrasound transducing device 2. This device 2 comprises an array 13 of individual ultrasound transducing elements 13a. The ultrasound transducing device 2 is for both emitting ultrasonic waves 11 and for receiving echo signals 12 from the object 3 being examined. The individual ultrasound transducing elements 13a of the array 13 may be micromachined ultrasound transducers (MUT), which are known in the art. Such element 13a may be formed by processing a small drum with a suspended membrane on top of a small cavity. The dimensions of this cavity in combination with the stiffness of the membrane will determine the resonance frequency of a particular

[0098] MUT. The MUT may be driven by the piezo-electric effect, forming a pMUT, which functions by applying an AC electric field at the resonance frequency across a piezoelectric material to generate a stress difference between the piezo-electric material and the membrane. This will induce a vibration and the emission of an acoustical wave. Typical frequencies are in the range of 50 kHz to 20 MHz. This translates into wavelengths ranging from 1 cm down to <100 um. Applications that use beam-forming to create a focal spot in emission or to image a small spot in receiving, may require larger arrays of ultrasound transducing elements 13a working together.

[0099] The system 10 further comprises an acoustic coupling interface 1 as disclosed herein above. The interface 10 is removably attached onto an outer surface 2a of the transducer 2 between the transducer 2 and the object 3 being examined. The object 13 may be a part of a body, such as an arm or a leg. The acoustic coupling interface 1 thus provides for bidirectional coupling such that the ultrasound signals 11 emitted by the transducer 2 are transmitted into the object 3 and the resultant echo signals 12 from the object 3 are transmitted back to the array 13a of the transducer 2.

[0100] The ultrasound transducing elements 13 a are configured for generating ultrasonic energy propagating along a main transducer axis parallel to Z-axis, and the flexible ultrasound transducing device 2 may comprise a first outer surface 2a facing the curved object 3 during examination. This first outer surface 2a of the transducer 2 thus has a normal vector that is parallel to the main transducer axis, and the acoustic coupling interface 1 is arranged between the object 3 and the transducer 2 with the first outer planar surface 4a of the sheet 4 facing the first outer surface 2a of the transducer 2. In the embodiments illustrated in FIG. 2a, a gel 14 is applied between the flexible ultrasound transducer 2 and the acoustic coupling interface 1 and between the acoustic coupling interface 1 and the object 14 being examined.

[0101] FIG. 4b shows an embodiment of the system 10 in which the waveguiding structures 6 of the acoustic coupling interface 1 has protruding portions 6a on the second planar surface 4b of the sheet 4. This provides for ultrasonic examination of the curved object 3 without having a gel between the acoustic coupling interface and the object 3. The protrusions 6a may facilitate adhesion of the interface 1 and the whole system 10 to the object 3 being examined. It may also be beneficial is certain applications to have a dry contact between object 3 and the system 10.

[0102] FIG. 4c shows an embodiment of the system 10 in which the waveguiding structures 6 of the acoustic coupling interface 1 has protruding portions 6a on the first planar surface 4a of the sheet 4. This provides for ultrasonic examination of the curved object 3 without having a gel between the acoustic coupling interface and the ultrasonic transducer. In analogy with the embodiment shown in FIG. 4b, the protrusions 6a may aid in the adhesion of the interface 1 to the flexible ultrasound transducer 2. It may be beneficial is certain applications to have a dry contact between the ultrasound transducer 2 and a disposable acoustic coupling interface 1.

[0103] FIG. 4d shows the use of the system 10 for examining a curved object 3. As illustrated in FIG. 4d, the flexibility of the sheet 4 makes it possible for the whole interface 1 to conform to the curved surface of the object 3 during examination, Further, the flexibility of the acoustic coupling interface 1 also makes it possible for the flexible ultrasound transducer 2 to conform to the curvature of the curved object 2 during examination. In this embodiment, neither a gel between the acoustic coupling interface 1 and the ultrasonic transducer 2 nor a gel between the acoustic coupling interface and the object 3 is used. Consequently, the acoustic coupling interface provides for a dry contact during examination and thus the exclusion of a gel, which may be practical benefit in various applications.

[0104] The system as disclosed in FIGS. 4a-4c is for creating data representative of features of an object 3. The data obtained may for example be used by a control unit 15 in the system 10 for creating an image of the internal of the object 3. The control unit 15 may comprise a communication interface, such as a transmitter/receiver, via which it may receive and transmit data from and to the ultrasound transducer 2. The control unit 15 may comprise a processing unit, such as a central processing unit, for calculating image parameters using the data obtained from the ultrasound transducer 2. Such a processing unit may be configured to execute computer code instructions which for instance may be stored on a memory.

[0105] FIG. 5 schematically illustrates a method 100 of obtaining data representative of features of an object. The method 100 comprises subjecting 101 the object to ultrasound signals using a system 10 as disclosed herein above for creating data representative of features of an object 3.

[0106] Further, the method 100 comprises analysing (102) the resultant echo signals from the object 3 and thereby obtaining data representative of features of said object based on the resultant echo signals. The analyses may for example be performed by a control unit as discussed in relation to FIG. 4d above.

[0107] The step 101 of subjecting the object to ultrasound signals may be performed with a direct contact of the acoustic coupling interface 1 and the object 3, such as shown in FIG. 4b, with a direct contact of the acoustic coupling interface 1 and the flexible ultrasound transducing device 2, such as shown in FIG. 4c above, or with a direct contact of the acoustic coupling interface 1 with the object 3 and the ultrasound transducer 2, such as shown in FIG. 4d.

[0108] In the above the inventive concept has mainly been described with reference to a limited number of examples. However, as is readily appreciated by a person skilled in the art, other examples than the ones disclosed above are equally possible within the scope of the inventive concept, as defined by the appended claims.